Corolla 2006-2007

Engine Coolant Temperature Sensor

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Operation



Specific to:

Toyota Corolla 2006-2008

The ECT sensor is used to monitor the ECT. The ECT sensor has a built-in thermistor with a resistance that varies according to the temperature of the engine coolant. When the ECT is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in the resistance are reflected in the voltage output from the ECT sensor.

The ECM monitors the sensor voltage and uses this value to calculate the ECT. If the sensor voltage output deviates from the normal operating range, the ECM interprets this deviation as a malfunction in the ECT sensor and sets the DTC.

Examples:



Upon starting the engine, the ECT is between 35°C and 60°C (95°F and 140°F). If, after driving for 250 seconds, the ECT change is within 3°C (5.4°F) of the staring temperature, the DTC is set (2 trip detection logic).
 
Upon starting the engine, the ECT is over 60°C (140°F). If, after driving for 250 seconds, the ECM change is within 1°C (1.8°F) of the starting temperature, the DTC is set (6 trip detection logic).
 

Removal & Installation



Specific to:

Toyota Corolla 2006-2008

  1. Disconnect coolant temperature sensor connector.
  2.  
  3. Using appropriate service tool, remove coolant temperature sensor.
  4.  

To install:

Click image to see an enlarged view

Fig. Removing engine coolant temperature sensor

  1. Reverse removal procedure.
  2.  

Testing



Specific to:

Toyota Corolla 2006-2008

  1. Possible causes:

    Click image to see an enlarged view

    Fig. Possible causes chart

  2.  
  3. Use wiring diagrams to test resistance in sensor and circuit.
  4.  
  5. If sensor is not within standard specifications, replace sensor.

    Click image to see an enlarged view

    Fig. Testing coolant temperature sensor



    Click image to see an enlarged view

    Fig. Standard resistance chart



    Click image to see an enlarged view

    Fig. Coolant temperature sensor pinout

  6.  

 
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